JPS6233352Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a new and improved mounting structure for mounting electronic components such as chip carrier type or flat package type LSI on a printed circuit board.

Conventionally, chip carrier type LSIs and the like have been mounted on a printed circuit board by soldering directly onto the printed circuit board, or as shown in FIG. 1, a plastic frame 2 is fixed onto the printed circuit board 1. An elastic connector 3 having an anisotropic conductive structure is placed inside this frame, an LSI chip carrier 4 is closely placed on this connector, a fixing jig 5 is placed on this chip carrier, and this is A device that engages with the frame 2 is known.

On the other hand, as a structure for mounting a flat package type LSI etc., for example, as shown in FIG. After screen-printing a paste made by kneading with flux, the connecting terminal pins 61 of the flat package 6 are placed on the terminal electrodes 11 in an aligned state, and then heated to form the terminal electrodes 11. A device in which the terminal pin 61 and the terminal pin 61 are integrated by brazing is known.

However, in the case of the former mounting structure, when soldering is used, when the chip carrier is made of ceramic, there is a large difference in expansion coefficient between the chip carrier and the board, and the soldering may peel off during a heat cycle test. Otherwise, as shown in FIG. 1, the mounting structure becomes bulky due to the need for a frame 2 for fixing the chip carrier 4 and the elastic connector 3. The problem is that the original purpose of increasing the density cannot be achieved, and in the latter mounting structure, when the solder powder paste is heated and melted, the terminal electrode 11 and the terminal pin 61 tend to be misaligned, The solder flows between the electrodes 11 or the pins 61.
There are disadvantages in that it is easy to short-circuit between them, and the brazing work is not a little difficult, and in any case, the mounting structure is not completely satisfactory.

The present invention provides a new and improved mounting structure capable of solving the difficulties in the conventionally known mounting structures, which consists of a connecting terminal section consisting of a parallel conductive path of a chip carrier or a flat package, An elastic connector having an anisotropic conductive structure made by integrally molding a conductive rubber member and an insulating rubber member is interposed between the connecting terminal portion consisting of parallel conductive paths of the printed circuit board on which this is to be mounted. The surfaces of the two connecting terminal portions and the surface of the connector in contact therewith are bonded and integrated via an adhesive layer, and the height of the connectors dispersed in the conductive rubber member and oriented in the conductive direction of the connector is increased. The present invention is characterized in that the end portion of at least a portion of the substantially short conductive linear body protruding from the surface of the conductive rubber member is brought into resilient contact with the surface of the connection terminal portion. According to this method, both a chip carrier and a flat package can be mounted on a printed circuit board using a common elastic connector, and the mounting work efficiency can be significantly improved.

The present invention will be described in detail below with reference to FIGS. 3 to 7.

Figure 3 shows the rod-shaped elastic connector 7.
This is used to mount the flat package 6 on the printed circuit board 1. In FIGS. 4 and 5, the flat package 6 and the This figure shows a structure in which a chip carrier 4 is mounted on a circuit board 1. 6a and 6b respectively illustrate different embodiments of the rod-shaped connector that can be used in the mounting structure shown in FIG. 3, and FIG. 6c shows a square ring that can be used in the mounting structure shown in FIGS. 4 and 5. This is an example of a shaped elastic connector.

Therefore, in the mounting structure according to the present invention, the configuration of the elastic connector 7 used therein, and the adhesive layer 8 (see FIG. 7) between the flat package 6 or chip carrier 4, the connector 7, and the printed circuit board 1, respectively. The most distinctive feature is that it is integrated by adhesive.

That is, as shown in FIGS. 6a to 6c, the connector 7 used in the mounting structure of the present invention has a conductive rubber-like elastic member 71 and an insulating rubber-like elastic member 71, similar to conventionally known elastic connectors of this type. It has an anisotropic conductive structure in which the member 72 is integrally molded in various forms, and as the conductive rubber-like elastic member, as shown in FIG. 7, a molded body made of a conductive rubber-like elastic material is used. A large number of conductive linear bodies or fibrous bodies 71b are dispersed and oriented in 71a, and the length of the linear bodies or fibrous bodies 71b is substantially shorter than the height of the molded body 71a in the orientation direction. In addition, at least a portion of the linear or fibrous body 71b has ends protruding from the surface of the molded body 71a substantially perpendicular to the orientation direction. Although Fig. 7 shows an example in which the conductive linear bodies are uniformly dispersed and oriented in the molded body, it is assumed that the linear bodies are unevenly distributed near the upper and lower surfaces. Of course it's a good thing.

The conductive rubber-like elastic material constituting the conductive rubber-like elastic member 71 is made of natural rubber, various synthetic rubbers, or various synthetic resins that exhibit rubber-like elasticity after molding and hardening, and carbon black powder or various metals as a conductivity imparting agent. It is composed of a conventionally known conductive rubber-like elastomer composition made by dispersing a predetermined amount of powder.On the other hand, the conductive linear or fibrous body may also include carbon fibers, various metal fibers or fine wires. It is made of a material substantially similar to that used in conventionally known anisotropic conductive members of this type.

In order to manufacture this conductive member 71, for example, the conductive linear body is dispersed and blended together with various powdered conductivity imparting agents in an insulating rubber-like elastic material, and then the conductive wire is mixed with a conventional extrusion method or calendar method. During the forming process, the conductive linear body is appropriately cut into pieces and subjected to shear stress to be uniformly dispersed and oriented. Conductive molded bodies are dispersed and oriented in the molded body, even though the rubber-like elastic body shrinks during cooling and hardening after molding (for example, silicone rubber shrinks by approximately 2.5% when cooled from 180°C to room temperature). Since the conductive linear body hardly shrinks, a certain degree of tightening force is acting on the conductive linear body in its longitudinal direction. Therefore, when this conductive molded body is cut into a desired shape, the above-mentioned tightening force is released on the cut plane that is substantially perpendicular to the direction of orientation of the conductive linear body, and as a result, the cut plane has no traces. As shown in FIG. 7, the ends of some of the conductive linear bodies 71b come to protrude.

The elastic connectors shown in FIGS. 6a to 6c are formed by integrally molding the conductive rubber-like elastic member 71 obtained as described above together with the insulating rubber-like elastic member 72. All of the elastic connectors shown in a to c have a conductive linear body 71b on the surface of the conductive member 71 that is involved in conduction.
Needless to say, the end portion of the holder is protruding.

In addition, in the mounting structure of the present invention, the connection terminal pin 61 of the flat package 6 or the chip carrier 4 or the connection lead-out terminal electrode (not shown in FIG. terminal electrode is formed)
and the connecting terminal electrodes 11 on the printed circuit board 1 are bonded together via an adhesive layer 8, and this adhesive layer 8 is made of synthetic resin such as urethane, diene, or silicone. The adhesive layer 8 can be formed by applying a rubber adhesive or a hot melt adhesive to the connector surface by dipping, printing, brushing, spraying, etc. It can also be provided by placing and integrating an adhesive film, which has been separately formed into a film shape, on the surface of the connector.

Note that the conductive rubber-like elastic member 7 of the connector 7
The amount of protrusion of the conductive linear body 71b in No. 1 is usually about 5 to 500 μm, and the thickness of the adhesive layer 8 is preferably smaller than the protrusion height of the conductive linear body 71b. However, when the adhesive layer 8 is brought into contact with the connecting terminal electrode 11 or the connecting pin 61 and a pressing force is applied during use, the adhesive layer 8 plastically flows and connects the protruding end of the conductive linear body 71b to the terminal. If the conductive wire body 71b can be easily brought into contact with the surface of the electrode or terminal pin, this thickness may be greater than the protrusion height of the conductive linear body 71b.

In the mounting structure of the present invention, when the connector 7 is clamped between the terminal pins 61 of the flat package 6 or the terminal electrodes of the chip carrier and the terminal electrodes 11 of the circuit board 1, first the connector 7 is mounted. Conductive rubber-like elastic member 7
The ends of the conductive linear body 71b protruding through the adhesive layer 8 from the upper and lower surfaces of the wire 71b come into contact with the surfaces of the terminal pins and terminal electrodes, and the ends of the linear body 71b are conductive without being bent. It will be pushed into the inside of the rubber-like elastic member 71. In this case, the lengths of the ends of the linear bodies 71b protruding from the upper and lower surfaces of the member 71 are irregular within the range of 5 to 500 μm as described above, but as described above, the terminal electrodes and terminal pins,
In other words, when pressing and clamping between connected objects,
The longer one is pushed deeper into the member 71, and the shorter one is pushed more shallowly into the member 71, and as a result, all of the protruding ends of the linear body 71b come into contact with the surface of the object to be connected. Even if the pressure contact load is removed after the agent 8 has hardened, the connected objects 11 and 6
A good conductive state can be maintained between the two.
This is done by connecting the protruding end of the conductive linear body 71b to the connected bodies 11 and 6 through the adhesive layer 8 under the action of the pressure welding load.
1, the conductive linear body 71
b is pushed into the conductive rubber-like elastic member 71, in other words, the protruding end of the linear body 71b is brought into elastic contact with the surfaces of the objects 11 and 61 to be connected, and in this state, the adhesive Since the layer 8 is hardened and fixed, even after the pressure contact load is removed, the protruding end of the linear body 71b can remain in resilient contact with the surface of the connected bodies 11, 61. It's for a reason.

Regarding the elastic connector used in the mounting structure of the present invention, if it is formed by providing hot-melt adhesive layers with different heat melting temperatures on one surface and the other surface involved in conduction, When mounting it, first, it is bonded to one connection terminal through an adhesive layer that melts at a low temperature, and then to the other connection terminal through an adhesive layer that melts at a high temperature. This greatly contributes to automating the mounting process, as mounting can be done in stages, and the same effect can be achieved when using adhesives with different curing speeds. is obtained.

Although the case where an LSI flat package or chip carrier is mounted on a printed circuit board has been mainly explained here, the mounting structure of the present invention is not limited to this, and includes, for example, magnetic bubble memory, ROM memory, etc. Of course, it can be applied as a mounting structure for various electronic devices.

As explained above, according to the mounting structure of the present invention, unlike conventional mounting structures of this type, there is no need to adopt separate mounting structures for the flat package and the chip carrier, but a single form is achieved using an elastic connector. Moreover, the mounting can be completed simply by bonding and integrating, which not only improves the mounting workability but also significantly reduces the cost required for this mounting structure. In the connector used in this structure, the end of the conductive wire body protrudes from the connector surface, so the electrical contact with the surface of the connected object is extremely stable, and the contact resistance value changes due to vibrations and shocks. Even if there is extremely small dirt or a thin oxide film or sulfide film on the surface of the object to be connected, these dirt and insulating films can be easily penetrated or broken by the protruding ends of the conductive wire during pressure-welding. Therefore, its electrical reliability is high, and its practical value is therefore extremely large.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view showing a conventional chip carrier mounting structure, and FIG. 2 is a perspective view of a conventional flat package mounting structure. 3 and 4 are perspective views showing different embodiments of the flat package mounting structure according to the present invention, and FIG. 5 is a perspective view showing an embodiment of the chip carrier mounting structure according to the present invention. 6a to 6c are perspective views illustrating different embodiments of the elastic connector that can be used in the mounting structure of the present invention, and FIG. 7 is an enlarged sectional view of the main part of the connector. DESCRIPTION OF SYMBOLS 1... Printed circuit board, 11... Connecting lead terminal electrode, 2... Frame, 3... Elastic connector, 4... Chip carrier, 5... Fixing jig, 6... Flat package, 61... Connection terminal pin, 7...Elastic connector, 7
1... Conductive rubber-like elastic member, 71a... Conductive rubber molded body, 71b... Conductive linear body, 72...
Insulating rubber-like elastic member, 8...Adhesive layer.

Claims (1)

[Scope of utility model registration request] A conductive rubber member and an insulating rubber member are integrated between the connection terminal portion of the chip carrier or flat package consisting of parallel conductive paths and the connection terminal portion of the printed circuit board on which it is to be mounted. A chemically molded elastic connector having an anisotropic conductive structure is interposed, and the surfaces of the two connecting terminal portions and the surface of the connector in contact therewith are bonded and integrated via an adhesive layer, and the conductive rubber member The end portions of at least some of the conductive linear bodies, which are substantially shorter than the height of the connector and are dispersed therein and oriented in the conduction direction of the connector, protrude from the surface of the conductive rubber member and elastically touch the surface of the connection terminal portion. A mounting structure for a chip carrier or flat package characterized by a contacting structure.